PLZZZ I will give brainiest and 90 points PLZ question 6 is soo confusing plzzz

Multiply. −2x(6x4−7x2+x−5) express the answer in standard form. enter your answer in the box.

Which pair of angles are vertical angles? ∠1 and ∠4 ∠1 and ∠2 ∠2 and ∠4 ∠2 and ∠3

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?